The inductive charging device has here a charging assembly with at least one secondary coil, wherein through a coupling of the secondary coil with a primary coil, the energy store of the motor vehicle is able to be charged. The secondary coil can, for example, be fastened to a motor vehicle floor, so that by the starting of a charging site which is level with the floor or is vertically adjustable, the secondary coil can be coupled with the primary coil. The primary coil and the secondary coil can be configured here for example in the form of a spiral flat coil or double-D coil.
In the charging process, an electric and a magnetic field are built up between the secondary coil and the primary coil, which enable an energy transfer from the source, which is connected in an electrically conducting manner with the primary coil, to the energy store, which is connected in an electrically conducting manner with the secondary coil. Through a magnet plate which is ferrimagnetic or ferromagnetic at least in some regions—for example with soft magnetic ferrites—in the charging assembly, the course of the magnetic and of the electric field can be influenced, in order to reduce the charging losses.
In the charging process, magnetic and electric field emissions occur, the extent of which increases with the charging power. The field emissions are shielded, so as not to damage electronic equipment in the motor vehicle and to preclude effects on a person's health. For the shielding of the field emissions, the inductive charging device has an emission protection assembly with a metal shielding plate—for example made of aluminium—which can intercept the field emissions during the charging process. Such inductive charging devices are known for example from EP 2 515 314 A1.
With the increasing charging power, the amount of heat arising on the magnet plate and on the metal shielding plate also increases, which is to be emitted to the environment. In the case of a high charging power, the heat can only be partially dissipated, which can lead to an overheating of the inductive charging device and to its being damaged. In order to enlarge the heat-emitting surface of the metal shielding plate, the dimensions of the metal shielding plate and consequently the structural volume and the weight of the inductive charging device are increased.